Disc brake boot seal method and article

Abstract

A disc brake boot seal 10 (and method for assembling a disc brake system) that is molded in its extended condition and that when moved into its collapsed condition will remain in its collapsed condition. The boot seal comprises a molded elastomeric sleeve 12 having a plurality of different wall portions 20-34 certain ones of which interact to releasably hold the sleeve in its collapsed condition so that it does not self-extend. The expense and high mold breakage resulting from the prior art system of molding a seal in its collapsed, convoluted condition are eliminated by this invention.

We claim: 
     
       1. A disc brake boot seal for sealing between the bore wall of a cylinder and a piston extending through the bore, comprising: (a) an annular, molded, unitary, one-piece flexible, elastomeric sleeve that is collapsible from an extended, as-molded condition to a collapsed convoluted condition and comprising in its extended condition a plurality of different, annular wall portions serially connected together from a piston sealing end at the axially outer end thereof to a cylinder sealing end at the axially inner end thereof, said piston sealing end having a smaller as-molded inner diameter than that of said cylinder sealing end, said wall portions allowing said sleeve to collapse from said extended, as-molded condition to a collapsed condition, and   (b) at least one of said wall portions including means for interacting with at least one of said wall portions for releasably holding said sleeve in said collapsed condition such that said sleeve does not self extend, and wherein said sleeve includes, in its extended condition, a cylindrical, relatively thick stabilizing wall, an intermediate flex wall located immediately axially inwardly of said stabilizing wall, thereby being located closer to said cylinder sealing end than is said stabilizing wall, said flex wall being connected to one end of said stabilizing wall and tapering radially outwardly from said one end of said stabilizing wall, and a tapered frustoconical upper flex and rolling wall immediately axially inwardly of and connected to said flex wall and having an inside diameter greater than that of said stabilizing wall, said flex wall including an annular crease on its radially outer surface and said upper flex and rolling wall being invertable about said crease, such that said upper flex and rolling wall inverts and moves from its position in the extended sleeve wherein it extends axially inwardly from said crease to an inverted position in the collapsed sleeve wherein it extends axially outwardly from said crease as said sleeve is moved from its extended to its collapsed condition.   
     
     
       2. The article according to claim 1 wherein said intermediate flex wall has a tapered radially inner surface which is substantially straight, which forms an acute angle with the axis of said seal and which tapers from a smaller to a larger diameter in the axially inward direction when said sleeve is in its extended condition. 
     
     
       3. The article according to claim 2 wherein said acute angle is approximately 25°. 
     
     
       4. The article according to claim 1 wherein the radially outer surface of said intermediate flex wall includes, when said sleeve is in its extended condition, an axially outer generally cylindrical surface and a generally radial surface located axially inwardly from said generally cylindrical surface, said outer and inner surfaces meeting at an annular crease. 
     
     
       5. The article according to claim 4 wherein said intermediate flex wall has a tapered radially inner surface which is substantially straight, which forms an acute angle with the axis of said seal and which tapers from a smaller to a larger diameter in the axially inward direction when said sleeve is in its extended condition. 
     
     
       6. The article according to claim 5 wherein said acute angle is approximately 25°. 
     
     
       7. The article according to claim 6 wherein said tapered frusto-conical upper flex and rolling wall tapers from a narrow thickness to a greater thickness in the axially outward direction when said sleeve is in its extended condition and wherein said tapered frusto-conical upper flex and rolling wall has a radially outer surface extending substantially axially. 
     
     
       8. The article according to claim 7 wherein said stabilizing wall is substantially cylindrical. 
     
     
       9. The article according to claim 8 wherein said stabilizing wall has a substantially uniform thickness throughout its length and wherein said thickness is substantially greater than that of said upper boot wall and of said lower flex wall. 
     
     
       10. A disc brake boot seal for sealing between the bore wall of a cylinder and a piston extending through the bore, comprising: (a) an annular, molded, unitary, one-piece, flexible, elastomeric sleeve that is collapsible from an extended, as-molded, condition to a collapsed convoluted condition, said sleeve having a sealing bead portion at one end thereof and a cylinder sealing portion at the other end thereof, said bead portion having a smaller as-molded inner diameter than that of said cylinder sealing portion, said sleeve comprising nine distinct annular wall portions of a plurality of different thicknesses serially connected together and comprising in order from said bead portion:   (1) said sealing bead adapted to elastically fit into an annular recess of a piston;   (2) an upper boot wall;   (3) an upper flex wall;   (4) a stabilizing wall;   (5) an intermediate flex wall;   (6) a tapered frusto-conical upper flex and rolling wall;   (7) a lower flex wall;   (8) a tapered frusto-conical lower flex and rolling wall;   (9) a sealing end adapted to be connected to a cylinder; and   (b) wherein at least one of said wall portions includes means for interacting with at least one of said wall portions for releasably holding said sleeve in its collapsed condition such that it does not self-extend.   
     
     
       11. The article according to claim 10 wherein said intermediate flex wall has a tapered radially inner surface which is substantially straight, which forms an acute angle with the axis of said seal and which tapers from a smaller to a larger diameter in the axially inward direction when said sleeve is in its extended condition. 
     
     
       12. The article according to claim 11 wherein said acute angle is approximately 25°. 
     
     
       13. The article according to claim 10 wherein the radially outer surface of said intermediate flex wall includes, when said sleeve is in its extended condition, an axially outer generally cylindrical surface and an axially inner generally radial surface, said cylindrical and radial surfaces meeting at an annular crease. 
     
     
       14. The article according to claim 13 wherein said intermediate flex wall has a tapered radially inner surface which is substantially straight, which forms an acute angle with the axis of said seal, and which tapers from a smaller to a larger diameter in the axially inward direction when said sleeve is in its extended condition. 
     
     
       15. The article according to claim 14 wherein said acute angle is approximately 25°. 
     
     
       16. The article according to claim 15 wherein said tapered frusto-conical upper flex and rolling wall tapers from a narrow thickness to a greater thickness in the axially outward direction when said sleeve is in its extended condition and wherein said tapered frusto-conical upper flex and rolling wall has a radially outer surface extending substantially axially. 
     
     
       17. The article according to claim 16 wherein said stabilizing wall is substantially cylindrical. 
     
     
       18. The article according to claim 17 wherein said stabilizing wall has a substantially uniform thickness throughout its length and wherein said thickness is substantially greater than that of said upper boot wall and of said lower flex wall. 
     
     
       19. The article according to claim 10 wherein said tapered frusto-conical upper flex and rolling wall tapers from a narrow thickness to a greater thickness in the axially outward direction when said sleeve is in its extended condition. 
     
     
       20. The article according to claim 10 wherein said stabilizing wall is substantially cylindrical. 
     
     
       21. The article according to claim 20 wherein said stabilizing wall has a substantially uniform thickness throughout its length and wherein said thickness is substantially greater than that of said upper boot wall and of said lower flex wall. 
     
     
       22. The article according to claim 10 wherein said tapered frusto-conical lower flex and rolling wall tapers from a narrow to a greater thickness in the axially inward direction when said sleeve is in its extended condition. 
     
     
       23. The article according to claim 10 wherein said lower flex wall includes a curving radially outer surface and a substantially parallel curving radially inner surface and wherein said lower flex wall curves from a larger diameter to a smaller diameter in the axially outer direction when said sleeve is in its extended condition. 
     
     
       24. The article according to claim 10 wherein said tapered frusto-conical upper flex and rolling wall has a radially outer surface extending substantially axially. 
     
     
       25. The article according to claim 10 wherein said tapered frusto-conical lower flex and rolling wall has a radially inner surface extending substantially axially. 
     
     
       26. The article according to claim 10 wherein said upper boot wall, in its as-molded condition, forms an acute angle with said stabilizing wall. 
     
     
       27. The article according to claim 10 wherein said seal includes an annular metal shell bonded to said sealing end. 
     
     
       28. The article according to claim 27 wherein said shell includes a cylindrical portion and a radial flange extending radially outwardly from the axially outer end of said cylindrical portion. 
     
     
       29. A method for assembling a disc brake system including a piston, a cylinder, and a disc brake boot seal for sealing the annular space between the piston and cylinder, comprising the steps of: (a) molding in its extended condition, an annular, unitary, one-piece, flexible, elastomeric sleeve that is collapsible from an extended as-molded, condition to a collapsed convoluted condition and that includes a plurality of different, annular wall portions serially connected together from a piston sealing end at one end thereof to a cylinder sealing end at the other end thereof, at least one of said wall portions having means for interacting with at least one of said wall portions for releasably holding the sleeve in its collapsed condition such that it does not self-extend;   (b) installing said sleeve in said cylinder of said disc brake system;   (c) collapsing said sleeve into its collapsed convoluted condition, and   (d) then installing a piston in said cylinder while said sleeve is in its collapsed condition wherein said collapsed sleeve is maintained in its collapsed condition without any external forces acting on said sleeve to maintain its collapsed condition, and attaching said piston sealing end to said piston.   
     
     
       30. The method according to claim 29 wherein said molding step comprises molding said sleeve with the following annular wall portions serially connected together starting at a piston sealing end thereof: (1) a sealing bead adapted to elastically fit into an annular recess of a piston;   (2) an upper boot wall;   (3) an upper flex wall;   (4) a stabilizing wall;   (5) an intermediate flex wall;   (6) a tapered frusto-conical upper flex and rolling wall;   (7) a lower flex wall; and   (8) a tapered frusto-conical lower flex and rolling wall; and   (9) a sealing end adapted to be connected to a cylinder.   
     
     
       31. The method according to claim 29 wherein said molding step comprises molding said sleeve with a relatively thin flex wall having a crease on its radially outside surface and providing a relatively thick stabilizing wall connected to said flex wall axially outside of said crease and providing a rolling wall connected to said flex wall axially inside of said crease and forming said rolling wall with a tapered thickness from a greater thickness adjacent said flex wall to a narrower thickness remote from said flex wall, and inverting said rolling wall such that it moves from axially inside to axially outside of said crease when said sleeve is collapsed, whereby said rolling wall, crease, and stabilizing wall hold said sleeve in its collapsed condition. 
     
     
       32. The method according to claim 31 wherein said sleeve installing step comprises installing said sleeve in said cylinder of said disc brake system while said sleeve is in its collapsed condition. 
     
     
       33. The method according to claim 31 wherein said sleeve installing step comprises collapsing said sleeve and then installing said sleeve in its collapsed condition.